With the wide application of an Internet protocol (Internet Protocol, IP) telephony technology, an enterprise or organization extends deployment of IP telephony from a central site to a remote branch office, and deploys a voice server at the central site to manage calls of the remote branch office in a centralized manner. To maintain continuity of basic calls and various voice services, when the communication between the branch office and the central site fails, a voice gateway of the branch office needs to take over the local voice call management function of the voice server of the central site to ensure normal proceeding of the local call of the branch office. After the communication is recovered after a failure, all calls are still processed by the voice server of the central site to implement centralized management of calls.
A SIP local survivable registration service emerges in the above situation. A server providing the SIP local survivable registration service can detect the status of the communication between the branch office and the voice server of the central site in real time, and can actively bear functions of the voice server when a communication failure occurs, for example, basic functions such as user registration and call services, and various voice service functions, which ensures continuity and stability of the communication between the branch office and the central site effectively.
The implementation of the SIP local survivable registration server is based on an assumption that each branch terminal of the branch office can obtain the address of a SIP registration server of the central site and the address of the SIP local survivable registration server of the branch office. In the prior art, generally the address of the SIP registration server of the central site and the address of the SIP local survivable registration server of the branch office are statically configured on each branch terminal of the branch office. However, the static configuration mode generates a large amount of configuration workload; in addition, because the branch office generally supports static configuration of addresses of at most two SIP registration servers, if the central site has an active SIP registration server and a standby SIP registration server, the address of the SIP local survivable registration server of the branch office cannot be statically configured any more. In this case, once the active and standby SIP registration servers of the central site fail, or a branch terminal cannot exchange information with the active and standby SIP registration servers, the branch terminal cannot work normally.